长江口北支中束窄工程对周边水动力及水质的影响

基于考虑水体斜压的MIKE3数值模型的HD模块和Ecolab模块,对长江口及附近海域水动力环境进行数值模拟,并将验证好的模型用于分析预测实施北支中束窄工程对周边水动力环境造成的影响。研究结果表明:中束窄工程围填后,北支流速均有一定程度的降低,北支上段汊口处受到南支涨潮的影响,涨急流速有增大趋势;北支束窄工程对盐度的影响趋势为北支区域盐度值有明显的降低,对枯季北支的盐度倒灌南支起到了明显的控制作用;工程实施后,北支河口处磷酸盐、无机氮与叶绿素a含量增加明显;北支中上段磷酸盐与无机氮平均浓度略有降低,而叶绿素a含量整体有上升趋势。工程围填对南支及外海区域的水动力特征及营养盐含量影响较小。

Influence of the North Branch middling narrowing on hydrodynamics and seawater quality in Yangtze Estuary

Based on the HD module and the Ecolab module of MIKE3 numerical model considering water baroclinic,the numerical simulation of hydrodynamic environment in the Yangtze River Estuary and adjacent waters is carried out.The verified model is used to analyze the influence of the North Branch middling narrowing project on the hydrodynamic environment.The results show thatthe flow velocity of the North Branch is reduced to a certain extentafter the narrowing project,and the flood velocity nearthe branch pointhas a tendency to increasein the upper segment of the North Branch,which is affected by the tides in the South Branch.The North Branch middling narrowing makes the salinity of the North Branch decrease obviously,and plays a controlling role on saltwater intrusion from the North Branch into the South Branch.The content of phosphate,inorganic nitrogen and chlorophyll-a obviously increases in the lower segment of the North Branch after the implementation of the project.The average concentration of phosphate and inorganic nitrogen decreases slightly,while the content of chlorophyll-a increases in the middle and upper segment of the North Branch.The North Branch middling narrowing has little effect on the hydrodynamic characteristics and nutrient content in the South Branch and offshore area.